Showing papers by "Arun Kumar published in 2006"

Homocysteine- and cysteine-mediated growth defect is not associated with induction of oxidative stress response genes in yeast

Abstract: Intracellular thiols like cysteine, homocysteine and glutathione play a critical role in the regulation of important cellular processes. Alteration of intracellular thiol concentration results in many diseased states; for instance, elevated levels of homocysteine are considered to be an independent risk factor for cardiovascular disease. Yeast has proved to be an excellent model system for studying many human diseases since it carries homologues of nearly 40% of human disease genes and many fundamental pathways are highly conserved between the two organisms. In the present study, we demonstrate that cysteine and homocysteine, but not glutathione, inhibit yeast growth in a concentration-dependent manner. Using deletion strains (str2Δ and str4Δ) we show that cysteine and homocysteine independently inhibit yeast growth. Transcriptional profiling of yeast treated with cysteine and homocysteine revealed that genes coding for antioxidant enzymes like glutathione peroxidase, catalase and superoxide dismutase were down-regulated. Furthermore, transcriptional response to homocysteine did not show any similarity to the response to H2O2. We also failed to detect induction of reactive oxygen species in homocysteine- and cysteine-treated cells, using fluorogenic probes. These results indicate that homocysteine- and cysteine-induced growth defect is not due to the oxidative stress. However, we found an increase in the expression of KAR2 (karyogamy 2) gene, a well-known marker of ER (endoplasmic reticulum) stress and also observed HAC1 cleavage in homocysteine- and cysteinetreated cells, which indicates that homocysteine- and cysteine-mediated growth defect may probably be attributed to ER stress. Transcriptional profiling also revealed that genes involved in one-carbon metabolism, glycolysis and serine biosynthesis were up-regulated on exogenous addition of cysteine and homocysteine, suggesting that cells try to reduce the intracellular concentration of thiols by up-regulating the genes involved in their metabolism.

Atropine-induced lens extrusion in an open eye surgery.

Abstract: A 2-month-old male baby undergoing penetrating keratoplasty (PKP) under general anesthesia developed bradycardia and a decrease in heart rate to 53 b x min(-1) when stay sutures were taken through the superior and inferior recti. A bolus of 0.1 mg intravenous atropine resulted in tachycardia of up to 180-220 b x min(-1), which persisted for 35 min. After corneal trephination was performed the eyeball seemed to pulsate with the heartbeat. Spontaneous extrusion of the lens and vitreous occurred, which necessitated a lensectomy and vitrectomy in addition to PKP. The role of atropine in corneal transplant surgery is discussed here.

Physical and morphometric characterization of Frieswal cattle

Abstract: The present investigation was undertaken to study the physical and morphometric characteristics in Frieswal cattle. The data pertained to 809 FrieswaI animals ofdifferent cat~ories. The physical characteristics included colour pattern of body, skin, tail switch, muzzle and hoof, length/size of tail, body, dewlap, naval flap, shape/size of udder/teat and udder appearance. Heart girth, body length and height and weights at different stages were taken up for morphometric characterization. The main body colour of Frieswal animals, was black and white (32% cows and 34% heifers) in different proportions varying from 10 to 90%. Skin colOti~ in majority of animals was black (53% cows and 48% heifers) followed by black and brown (36% cows and 46% helifers). The prominent colour oftail switch was white (47% cows and 35% heifers). Most of the animals had black muzzle (90% cows and 96% heifers). Hoofcolour was black in 57% cows and 59% heifers. Adult Frieswal cows were medium (39%) to large in size (56%) with medium dewlap (87%) and small naval flap (93%). Most ofthe animals were docile (83%). Udder was symmetrical in most ofthe cows (90%) and heifers (100%). Frieswal calves averaged 26.51 kg at birth, 66.69 kg at 3 months and 117.95 kg at 6 months of age. The body weight of the heifers was 257 kg at 18 month and 323 kg at 24 month of age. Weight at first calving averaged 412 kg. Body height, body length and heart girth averaged 122, 122 and 161 em in heifers; 129, 122 and 184 em in adult cows and 142, 148 and 208 cm in bulls.